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Genes pinpoint time of death of crime victims in 63.75 minutes


Genetics clocks that begin ticking after someone dies could help CSI teams better pinpoint time of death.<br />PHOTO CREDIT:

Genetics clocks that begin ticking after someone dies could help CSI teams better pinpoint time of death.

Forensics teams currently work out when someone has died using their body temperature, which falls by 1.5°C (2.7°F) an hour.

They can also guess it based on rigor mortis or using insects around the corpse. But a new study claims genes could provide a simpler way to pinpoint a time of death to within close to an hour.

Scientists have found a ‘cascade’ of genetic changes which happen when we die, which fuel the death of cells in the body and the shutdown of the immune system.

The clearest readings come from the skin, thyroid, subcutaneous fat and lungs, as genes no longer need to ferry oxygen from the lung to the rest of the body.

The researchers, who examined genes in 129 dead bodies, say they came up with a time of death accurate to within 63.75 minutes.

They say the method could be a ‘powerful tool’, noting that current forensic techniques may be unreliable and inaccurate.

However researchers, led by the Centre for Genomic Regulation in Barcelona, stress that their findings have not yet been proven to work beyond 24 hours after death.

Lead author Dr. Pedro Ferreira, from the University of Porto in Portugal, said: “We found that many genes change expression over relatively short post-mortem intervals, in a largely tissue specific manner.

“This information helps us to better understand variation and also it allows us to identify the transcriptional events triggered by death in an organism.”

Changes in the genes begin as soon as someone dies, with the most obvious ones seen between seven and 14 hours later.

While there are few immediate changes in areas of the body such as the spleen and the brain’s cerebellum, big changes are seen in the muscle and colon for example.

The study looked at gene expression – the process by which the instructions in our genes are converted into a functional product, like a protein.

They identified 187 important genes after death, including the HBA1 and HBA2 genes which transport oxygen from the lungs and change their behaviour after someone stops breathing.

Working out the time of death is described as a ‘problem of central importance’ in the study, which is published in the journal Nature Communications.

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